Thanks Teazer,
Looks like they're also about patience...
After last night's goodness, all has reverted back to normal in the non working sense.
I started the bike up in the morning and let it idle, just to see how it would perform. Started off great - it always seems to idle a bit higher at the beginning before quickly coming down to just below 1k. I messed around with the idle screw to get it to the 1.3k mark the manual recommends, and it was happy with that. All the meanwhile, white smoke continued to come out from the exhaust.
Revved it a bit and noticed 'dirty' smoke coming from the exhaust around the 3k mark. Not sure if its brown or black but lots of it, after which, the bike started to want to die on itself, and while I could keep it running by revving it more, it got harder and harder until it died.
Pulled the spark plug out again and noticed it was carbon fouled. Reasons for this seems to be the following:
1. rich mixture
2. weak ignition
3. poor compression
I tested my compression and got 110 PSI, which seems to be what I'm getting these days with a warm engine.
Cleaned the spark plug (just brushing some of the carbon off) and tried starting again. Bike did not want to start and I believe started backfiring. I'm calling it backfiring because I saw fuel mist shoot out from the jets holes in the carb, on the intake end, after removing the pod filter. This action produces a far amount of force and even managed to shift the carb loose from the manifold...
So reasons for backfiring according to a quick search on the internet are:
1. lean mixture
2. incorrect ignition timing
So continual issues which I am now facing are:
1. Bike idles fine, but has a tendency to want to die after giving it substantial throttle and revving past the 3k mark. As I am running the pod filter this most likely has to do with my jetting (running 130 main/68 secondary - originally 98 main/68 secondary)
2. White smoke, initially thought to be a result of overly high levels of oil, but after running it for a good 10 minutes or so on idle, the smoke is still there. May be pointing to issues with piston rings or valve seals?
3. Starting is unreliable and gets more and more difficult after each attempt.
Having seen the big difference the correct oil levels made to starting the bike, and seeing the continual white smoke, and linking that with the difficulty in starting (but not the backfiring, which is the main issue now) I'm thinking there may be an issue with the oil seals? I have read that I should be able to read the oil levels on the bike after letting it cool down for a couple minutes, but my oil levels never seem to return to the gauge very quickly - could this be pointing to an issue to how the oil may be impeded from returning back down?
Anyways, I think I should look into the backfiring first. Will try changing the secondary jet back to the 70 (one size up) and try to check the ignition timing. However, the manual says I need a strobe light, so I'll have to look into it. It also confuses me why this might happen now, when it was starting fine before. It definitely isn't the spark plug, as even though its fouled, I can see a clear spark from it.
Well, Swivel sent me some good motivation. A kz250 featured on pipeburn, from an Aussie builder!